Design and Theoretical Analysis of a Low Demodulation Deviation PhC Dual-Parameter Sensor Based on Quasi-BIC and Guided Mode Resonance

Achieving multiple resonances with high Q-factors, high sensitivities, and large modulation depths in photonic crystals (PhCs) is essential for high-precision multiparameter sensing. In this article, a silicon PhC slab driven by a quasi-bound state in the continuum (quasi-BIC) and guided mode resonance is theoretically proposed for refractive index (RI) and temperature sensing. By carefully engineering the structure of the PhC slab, the Q-factors, sensitivities, and modulation depths of the sensing modes are significantly enhanced. The Q-factors of quasi-BIC and guided mode resonance exceed $10^{{4}}$ , the sensitivities exceed 800 nm/RIU, and the modulation depths reach nearly 100%. Moreover, combining two resonances with high Q-factors and high sensitivities effectively reduces demodulation deviations. The demodulation deviations of RI and temperature are $5.1\times 10^{-{6}}$ RIU and $8.7\times 10^{-{2}}$ K, respectively. Compared with the previously reported dual-parameter sensors, the proposed sensor achieves lower demodulation deviation while maintaining competitive sensitivity, Q-factor, and modulation depth. The combination of quasi-BIC and guided mode resonance may inspire new design strategies for high-performance multiparameter sensors.